1. Field of the Invention
The invention concerns a method of operating a wind park and also a wind park as such.
2. Description of the Related Art
Wind power installations were initially always erected in the form of individual units and it is only in recent years that, caused also by administrative and building regulations, wind power installations are frequently installed in wind parks. In that respect a wind park in its smallest unit is an arrangement of at least two wind power installations, but frequently markedly more. By way of example mention may be made of the wind park at Holtriem (East Frisia) where more than 50 wind power installations are set up in an array. It is to be expected that the number of units and also the installed power of the wind power installations will also increase greatly in the forthcoming years. In most cases the wind potential is at its greatest in regions of the power supply networks with a low level of short-circuit power and low population density. It is precisely there that the technical connection limits are quickly reached by the wind power installations, with the result that it is then no longer possible for further wind power installations to be set up at such sites.
A conventional wind park which is connected, by way of example, to a 50 MW transformer substation can therefore provide, at a maximum, only 50 MW total power, that is to say for example 50 wind power installations each providing 1 MW nominal power.
Bearing in mind that wind power installations are not constantly operated in the nominal mode and thus the overall wind park also does not constantly reach its maximum power, referred to herein as the nominal power, it can be found that the wind park is not put to optimum use if the nominal power of the wind park corresponds to the maximum possible total power which can be fed into the electric grid connected to the wind park.
Another issue is that in the case of low-power electrical networks, some of which are called island networks, the network frequency rises very quickly and abruptly if a relatively large consumer is separated from the electrical network. The drive machines such as for example diesel engines, water wheels and the like require some time in order then to reduce their mechanical and electrical power. During that period of time those generators produce more energy than is taken from the electrical network. That energy is then consumed for accelerating the generators. That means that the rotary speed and thus also the network frequency rises.
As many electrical devices, for example computers, electric motors and the like, which are connected to the electrical network, are however not designed for fluctuating network frequencies or abrupt changes therein, that can result in damage to electrical machines, even going as far as destruction thereof.